A nationalist theory of the modern state holds that territorial states should be constituted as nations composed of people who in some sense belong with each other as members of their country. Liberal philosophers have defended this view on the grounds that nationality creates the solidarity necessary for social justice. Their argument is troubled by the case of the United States, where nationality is strong but solidarity weak. According to the best empirical studies, the fundamental reason for the American exception is not libertarian political culture, but white anti-black racism. This essay makes the case that an open border policy with Mexico and other Latina/o states is likely to weaken the national identity now widely held in the United States, but increase the political prospects for racial justice. It follows that a liberal nationalist justification for excluding undocumented Latina/o immigrants from membership in U.S. society should be rejected